SOUTH KINGSTOWN — The Supreme Court on Friday overturned the conviction of a woman convicted in a drunken-driving crash that shattered a Narragansett man’s leg, saying that the trial justice inappropriately questioned two witnesses and prejudiced the jury.

Nicki A. Nelson, now 47, was convicted in 2007 of driving under the influence and driving to endanger, both with serious injury resulting. The police said that on July 24, 2004, Nelson was driving a pickup truck down Route 1 that swerved into oncoming traffic and crashed head-on with a Saturn driven by Stanley Bates. The crash caused permanent disfiguration to Bates’ leg.

Her sentence of 10 years in prison was vacated, the high court said, because trial Judge Stephen P. Nugent’s questioning “took on an air of cross-examination.” A motion to set Nelson’s bail will be heard Monday in Washington Superior Court.

According to the decision, Nugent’s questioning of two witnesses — a laboratory technician from South County Hospital and the director of the Rhode Island State Crime Laboratory — was prejudicial because it “served as an extension of the direct and cross-examination and went beyond acceptable limits,” and it “severely prejudiced the defendant because it reinforced defendant’s intoxication to the jury.”

“Indeed, the trial justice noted after defense counsel’s objection that ‘I didn’t want the jury to be confused and that was my point in questioning [the technician], not to… as you put it, place the defendant in harm’s way,’ ” according to the decision. “He apparently did not believe that the jurors were confused, but rather did not want them to become confused with respect to the fifty-five page medical records.”

That distinction, though seemingly small, means that Nugent overstepped the boundaries of the questions that judges are allowed to ask of trial witnesses. According to the opinion, judges are allowed to ask questions that clarify confusing issues for the jury.

In questioning the technician, Nugent repeatedly asked why they were unable to perform a spinal assessment on Nelson when she was taken to the hospital. The witness replied that he couldn’t because of Nelson was too intoxicated to cooperate with the examination and to continue with the procedure would be akin to “malpractice” for him. The high court said that testimony, elicited by the judge, was “devastating” in a drunk-driving trial.

The opinion also states that Nugent rephrased a question already asked about whether the lab director had an opinion on if Nelson’s blood-alcohol level at the time of the crash would have changed by the time her blood was drawn an hour later. The director said he would like to know when Nelson’s last drink was prior to the accident. Analysis showed that her blood-alcohol level was between 0.192 percent and 0.208 percent. The legal limit is 0.08 percent in Rhode Island.

The court decided that three other issues raised in appeal — the chain of command of a blood sample, a potential juror’s outburst during voir dire and his failure to conduct an individual survey of each potential juror to see whether they could put the potentially inflammatory remarks of the outburst out of their minds — had no bearing on the outcome of the case.

tbuford@projo.com